This invention pertains to filters, and more particularly to a cooking oil filter constructed from filter paper having a closure that moves over an opening in the filter to enclose the frame.
Cooking oils, such as those used in commercial or institutional deep fryers, tend to become contaminated with such things as moisture and carbonized food particles during frying. The oils also tend to break down chemically after extended use, often causing the oil to foam, smoke, smell bad, look bad, or taste bad. It has been found that keeping the cooking oil clean by removing the particulate matter and filtering it on a regular basis tends to extend the useful life of the cooking oil, and increase the quality and appearance of foods which are cooked therein.
Accordingly, a variety of specialized systems and filter media for filtering cooking oil have been developed. In most oil filtering systems, the contaminated oil is transferred from the deep fryer to a holding reservoir, pumped under vacuum through a filter medium, and then returned to the deep fryer for further use. One widely used filter system has a flat filter frame made of rectangular top and bottom elements. Companies that manufacture and supply these frames, although not limited to the following, are Henny Penny Corporation, B K Industries, The Dallas Group, Giles Food Service Equipment and Broaster Pressure Fryers. The top and bottom elements are perforated and together make a holder to support the filter medium. The top and bottom elements also form a space in between to allow the oil to flow through the filter to a pump. In such a system, the filter medium can be formed from two carbon filter paper sheets, or one sheet folded over, so as to resemble a pouch. The pouch is formed by having three sides connected or in the case of the folded one sheet, by having two sides connected. The fourth side is open to allow the filter frame to slide in-between the upper and lower sheets of the pouch. The filter, now enclosing the frame is closed with clips or other mechanical devices. The frame may have a nipple which protrudes from the filter. The nipple can be inserted into a connector on a suction line of an oil recirculation pump. The pump provides the driving force to move the oil throughout the system. The frame keeps the filter medium from collapsing due to pressure created by the pump. The contaminated oil then flows through the filter, through the perforations in the frame, into the space created by the top and bottom elements of the frame, eventually reaching the suction line to the pump. The oil can be further processed if so desired. The filter prevents particles from reaching the pump and the remainder of the system. The filter may also neutralize any unpleasant tastes or odors.
The clips and mechanical devices currently used to seal the open end of the filter pouch are unreliable. The clips may not provide an integral seal between the two carbon filter paper sheets. As a result, some oil may bypass the filter through the spaces; the oil that is left unfiltered may lead to unpleasant tasting food. Since there is little resistance in the open spaces, the amount of oil that bypasses the filter can be substantial. The clips may also deform due to normal use which would eventually allow the clips to loosen or fall off.
Therefore, there is a need for a more effective closure for carbon filter paper pouches. The present invention, when used in conjunction with a filter frame element, will provide a more reliable means of closing a filter.
In accordance with this invention, an improved filter envelope is provided. The filter envelope for a filter frame includes an enclosure, the enclosure being constructed from planar first and second filter paper members lying atop one another. The first and second filter paper members each have a lateral, medial, base, and top sides; the lateral, medial, and base sides being connected to each other, respectively, to define the enclosure. The top side of the first member is not connected to the top side of the second member so as to define an opening in the enclosure to receive the frame. A closure is formed from a planar third filter paper member which is connected to a portion of the enclosure, proximate to the opening. The third filter paper member is movable between a first position and a second position, the second position being suited to close the opening.
In a preferred embodiment, an oil filter is constructed from one elongate sheet of filter paper medium having a lateral and a medial edge, the sheet being divided into a first, second, and third region. The first and second regions have lateral, medial, top and base sides. The third region requires at least a base side. The first region is contiguous with the second region such that the top side of the first region lies adjacent to the base side of the second region, and the second region being contiguous with the third region, such that the top side of the second region lies adjacent to the base side of the third region. The first and third regions are provided with an aperture for engaging a portion of the frame. The filter envelope of a preferred embodiment is formed by folding the first region along a line traversing the contiguous portion between the first and second regions, the line being from the lateral to the medial side. The lateral and medial sides of the first and second regions are then connected together to form an enclosure with an opening. In a preferred embodiment, the sides are stitched. The third region forms the closure for the filter envelope. The third region may be folded along a line traversing the contiguous portion between the second region and the third region, the line being from the lateral to the medial side. In a preferred embodiment, the filter paper medium includes carbon. The first and second regions are shaped to resemble rectangles, and the third region resembles a trapezoid.
In another embodiment, the oil filter is constructed from one irregular shaped sheet of filter paper medium. The filter paper medium has three regions. The first and second regions have lateral, medial, top and base sides. The third region requires at least a base side. The first and second regions are contiguous along the lateral side of one region and the medial side of the other region. The third region is contiguous with the second region such that the top side of the second region lies adjacent to the base side of the third region. The first and third regions are provided with an aperture for engaging a portion of the filter frame element. The filter envelope is formed by folding the first region along a line parallel to the lateral side or the medial side, depending on which side is contiguous to the second region. The fold will lie along a contiguous portion between the first and the second regions. Therefore, if the first region""s lateral side is contiguous to the medial side of the second region, the fold is along the contiguous portion connecting both regions. If the first region""s medial side is contiguous to the lateral side of the second region, the fold is also along the contiguous portion. In this embodiment, the base regions of the first and second members and the sides which were not contiguous will be connected to form an enclosure. The third region forms the closure for the filter envelope. The third region may be folded along a line traversing the contiguous portion between the second region and the third region, the line being from the lateral to the medial side. The first and second regions are shaped to resemble rectangles, and the third region resembles a trapezoid.
In another embodiment, an oil filter envelope is constructed from three separate and distinct filter paper sheets. The first and second filter paper sheets have lateral, medial, top and base sides. The lateral, medial and base sides are connected to one another respectively, forming an enclosure with an opening for the frame. The closure is formed by connecting a third filter paper sheet proximate to the opening. The third filter paper sheet may move to close the opening formed in the enclosure. The first and third filter paper sheets may have an aperture for engaging a portion of the frame. The first and second sheets resemble rectangles, and the third sheet is trapezoidal shaped.
In another embodiment, the oil filter may be constructed of two filter paper sheets. In this embodiment, one of the two filter paper sheets has two regions. The enclosure may be formed by the filter paper sheet having two regions, each region having lateral, medial, top, and base sides. The regions are contiguous along at least one side. The enclosure is formed by folding along a line in the contiguous portion. Two of the sides are connected to form the enclosure with an opening. The second filter paper sheet forms the closure and is connected proximate to the opening. The second filter paper sheet moves to close the opening. Alternatively, the enclosure may be formed from two filter paper sheets. A first filter paper sheet has lateral, medial, top and base sides, and the second filter paper sheet has two regions. A first region has lateral, medial, top, and base sides to match the lateral, medial, top, and base sides of the first filter paper sheet, and the second region has at least a base side, the base side being contiguous to the top side of the first region. The lateral, medial, and base sides of the first filter paper sheet are connected with the lateral, medial, and base sides of the first region to form the enclosure with an opening. The closure is formed from the second region of the second filter paper sheet. The second region moves along a transverse line in the contiguous portion between the first and second regions to close the opening.
A filter envelope formed in accordance with the present invention is an advancement over the prior art which uses only clips to hold and close the open end of the enclosure. A filter envelope of the present invention eliminates the need to have clips which may fall or otherwise be lost. In addition, a filter envelope of the present invention provides a better seal for the opening in the filter, leading to improved filtration of the cooking oil.